Preheat the oven to 425 degrees.
Wash and cut the potatoes into quarters. Arrange the potatoes cut side down on a rimmed baking sheet. Then pour in the water and cover the baking sheet with foil. Seal the edges around the baking sheet rim to tightly trap in the steam. Roast the potatoes for 20 minutes, or until a fork slides easily through the potato.
Remove the foil and pour out the water. Drizzle on the olive oil, season with a pinch of salt and pepper, and toss to coat. Arrange the potatoes with the cut side down. Turn the oven to 500 degrees and roast the potatoes for about 20 minutes or until the bottoms are deeply browned and crisp.
Meanwhile, in a blender combine the cashews, milk, garlic, lemon juice, Frank's and a pinch of salt and pepper. Blend until totally smooth and set aside until you are ready to serve.
Plate the potatoes with a drizzle of aioli, cracks of black pepper, salt and fresh parsley. Serve hot and crispy.